Thermoplastic molding compositions are being used in a wide variety of applications because of their attractive profile of mechanical and physical properties. A key property for many applications is the transparency of the composition. Blends of polycarbonates (PC1) and polyethylene terephthalate (PET) are known and have been used in applications where enhanced chemical resistance is desired. It has been the experience of workers in the art that the TLT values of blends of PET and polycarbonate are lower than those of the individual components. A commercial product containing terephthalates of ethylene glycol and cyclohexane dimethanol and polycarbonate is noted for its transparency. The relevant art is noted to include U.S. Pat. No. 5,104,723 which disclosed blends of PET with polycarbonate resins which resins are derived from diphenols, the structure of which includes special cyclic bridging units (PC2). Also relevant is U.S. Pat. No. 5,132,154 which disclosed blends of such PC2 with conventional polycarbonates, that is PC1.
It is an object of the present invention to provide a method for increasing the TLT of a thermoplastic composition containing PET and polycarbonate resin.
It is a further object of the invention to provide thermoplastic compositions containing PET and (co)polycarbonate having improved TLT.